This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Glioblastoma multiform (GBM) is by far the most malignant glioma. We have introduced a new treatment for GBMs that comprises the inhalation of a naturally occurring terpene with chemotherapeutic properties known as perillyl alcohol (POH). Clinical trial results on recurrent GBM patients showed that POH extends the average life by more than eight months, temporarily slows tumor growth, and in some cases even decreases tumor size. After approximately seven months, the tumor continues to grow and leads to a dismal prognosis. To investigate how these tumors become resistant to POH, we generated an A172 human glioblastoma cell culture tolerant to 0.06 mM of POH (A172r). We used Multidimensional Protein Identification Technology (MudPIT) to compare the protein expression profile of A172r cells to the established glioblastoma A172 cell line. Our results include a list of identified proteins unique to either the resistant or the nonresistant cell line. These proteins are related to cellular growth, negative apoptosis regulation, Ras pathway, and other key cellular functions that could be connected to the underlying mechanisms of resistance.